Facilitated activation of metabotropic glutamate receptors in cerebellar Purkinje cells in glutamate transporter EAAT4-deficient mice
- 作者：Osamu Nikkuni ; Yukihiro Takayasu ; Masae Iino ; Kohichi Tanaka ; Seiji Ozawa
- 关键词：Glutamate transporter ; EAAT4 ; GLAST ; EAAC1 ; Purkinje cell ; Metabotropic glutamate receptor ; EPSC ; Parallel fiber
- 刊名：Neuroscience Research
- 出版年：2007
- 期刊代码：53_01680102
- 类别：neu
- 出版时间：November 2007
- 卷：59
- 期：3
- 页码：296-303
- 文件大小：726 K
摘要
Around excitatory synapses in cerebellar Purkinje cells (PCs), GLAST and EAAT4 are expressed as predominant glial and neuronal glutamate transporters, respectively. EAAC1, another subtype of neuronal glutamate transporter, is also expressed in PCs. EAAT4 is co-localized with metabotropic glutamate receptors (mGluRs) at perisynaptic sites in excitatory synapses in PCs, and this neuronal transporter was reported to be involved in the regulation of mGluR activation induced by the stimulation of parallel fibers (PFs). However, it remains to be elucidated whether only EAAT4 is specifically involved in mGluR activation among the glutamate transporters expressed near excitatory synapses in PCs. Here we examined mGluR-mediated excitatory postsynaptic currents (mGluR-EPSCs) evoked by PF stimulation in cerebellar slices of mice deficient in EAAT4, EAAC1, or GLAST. PF-evoked mGluR-EPSCs showed larger amplitude and faster rising kinetics in EAAT4-deficient mice than in the wild-type mice. In contrast, there was no significant difference in either the amplitude or the rising kinetics of mGluR-EPSCs in GLAST- or EAAC1-deficient mice compared to wild-type mice. We conclude that EAAT4 is most closely involved in mGluR activation in PCs among the glutamate transporters.